Image distance sensor and manufacture method thereof as well as a ranging device

ABSTRACT

This disclosure provides an image distance sensor and a manufacture method thereof, as well as a ranging device. The image distance sensor includes a semiconductor substrate, and an image sensing unit and a distance sensing unit formed on the semiconductor substrate. The image sensing unit and the distance sensing unit are formed in a same manufacture process.

RELATED APPLICATION

The present application claims the priority of Chinese patentapplication for invention No. 201810749555.4, filed on Jul. 10, 2018,the entire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to the field of display technologies, and inparticular to an image distance sensor and a manufacture method thereof,as well as a ranging device.

BACKGROUND ART

Automobiles have become important vehicles for modern people, so thereis an important need of improving driving security. When a vehicletravels forward, the driver can see pedestrians, vehicles or targetsclearly, but when the driver wants to park at the wayside, reverse thevehicle into a garage or drive backward, he/she needs to know thesituation behind the vehicle with the help of a rear view mirror, areverse radar or a reverse image device.

Due to the structural characteristics of rear view mirrors, when thedriver observes a scene behind the vehicle with a rear view mirror,there can be a blind angle that is not observable, which increases therisk that the vehicle will bump into the targets or the pedestrians. Areverse radar is usually an ultrasonic sensor which measures distancesby means of echoes. When the reverse radar begins to work, the sensoremits an ultrasonic signal, and when there is an obstacle behind thevehicle, the ultrasonic signal will be reflected by the obstacle, andthe sensor will receive the reflected signal and process it by acontroller to determine the distance between the obstacle and the rearend of the vehicle. Although the reverse radar can accurately measurethe distance between the obstacle and the rear end of the vehicle, itcan only remind the driver of how far/close the rear end of the vehicleis from/to the obstacle by means of the frequency of beeps, and thedriver cannot see the shape and the position of the obstacle. A reverseimage device is usually provided with a camera device at the rear end ofthe vehicle so that the driver can see clearly the obstacle behind thevehicle through a display inside the vehicle. Although the reverse imagedevice can display the shape and the position of the obstacle in anintuitional manner, the driver cannot know the real distance between theobstacle and the rear end of the vehicle, and as a result, he/she has tostare at the display all the time.

Nowadays, a technical solution providing both a reverse radar functionand a reverse image function has been proposed in the prior art, inwhich the reverse radar directly measures a distance between the rearend of the vehicle and the obstacle and prompts the driver, and thedriver observes the display of the reverse image device upon receipt ofthe prompt and thus accurately learns about information of the scenebehind the vehicle. However, in the above technical solution, thereverse radar is an independent device, so is the reverse image device.They are actually a combined structure for implementing two functions byusing two separate parts respectively, which leads to defects such aslow integration, large volume, high costs and so on.

SUMMARY

The technical problem solved by the embodiments of this disclosure is toprovide an image distance sensor and a manufacture method thereof, aswell as a ranging device, so as to overcome the defects such as lowintegration, large volume, high costs and so on in the existing combinedsolution.

According to one aspect of this disclosure, an image distance sensor isprovided, comprising a semiconductor substrate and an image sensing unitand a distance sensing unit formed on the semiconductor substrate,wherein the image sensing unit and the distance sensing unit are formedin one and the same manufacture process.

In one embodiment, the image sensing unit comprises a pixel circuit anda photosensitive unit formed on the semiconductor substrate, the pixelcircuit comprises: a first well region and a second well region formedin the semiconductor substrate, the first well region being providedwith a first doping region and the second well region being providedwith a second doping region, and the first well region and the secondwell region having different semiconductor types; a first gate and asecond gate formed on the first well region and the second well region;a first insulating layer covering the first gate and the second gate;and a first source, a first drain, a second source and a second drainformed on the first insulating layer, wherein the first source and thefirst drain are connected with the first doping region through via holespenetrating the first insulating layer, the second source and the seconddrain are connected with the second doping region through via holespenetrating the first insulating layer, and the first drain is connectedand with the second source.

In an embodiment, the photosensitive unit comprises: a third well regionformed in the semiconductor substrate, the third well region beingprovided with a third doping region, and the third doping region and thethird well region having different semiconductor types; and a firstelectrode formed on the third doping region, the first electrode beingconnected with the second drain of the pixel circuit.

In an embodiment, the distance sensing unit comprises: a resonant cavityformed in the semiconductor substrate; a first insulating layer coveringthe resonant cavity; a piezoelectric layer formed on the firstinsulating layer; a second insulating layer covering the piezoelectriclayer; and a first drive electrode and a second drive electrode formedon the second insulating layer, the first drive electrode and the seconddrive electrode being connected with the piezoelectric layer through viaholes penetrating the second insulating layer respectively.

In an embodiment, the image distance sensor further comprises a firstlead wire, a second lead wire and a third lead wire formed on the secondinsulating layer, wherein the first lead wire is connected with thefirst source of the pixel circuit through a via hole penetrating thesecond insulating layer, the second lead wire is connected with thefirst drain and the second source of the pixel circuit through a viahole penetrating the second insulating layer, and the third lead wire isconnected with the second drain of the pixel circuit and the firstelectrode of the photosensitive unit through a via hole penetrating thesecond insulating layer.

In an embodiment, the image distance sensor further comprises a filterlayer, the filter layer including a plurality of filter units arrangedin an array, each of the filter units being used for transmitting lightof a color.

In an embodiment, the image distance sensor further comprises a lightcollection layer, the light collection layer including a plurality oflens units arranged in an array, the lens units being used forconverging incident light to the photosensitive unit of the imagesensing unit.

According to another aspect of this disclosure, a ranging device isprovided, comprising any image distance sensor mentioned above.

According to yet another aspect of this disclosure, a manufacture methodof an image distance sensor is provided, comprising: forming an imagesensing unit and a distance sensing unit on a semiconductor substrate inone and the same manufacture process.

In one embodiment, the step of forming an image sensing unit and adistance sensing unit on a semiconductor substrate in one and the samemanufacture process comprises: forming on the semiconductor substrate apixel circuit and a photosensitive unit of the image sensing unit, and aresonant cavity of the distance sensing unit; and forming an ultrasonicsensing unit on the resonant cavity.

In one embodiment, the step of forming on the semiconductor substrate apixel circuit and a photosensitive unit of the image sensing unit and aresonant cavity of the distance sensing unit comprises: forming in thesemiconductor substrate a first well region, a second well region and athird well region, the first well region having different semiconductortypes as the second well region, and the third well region having thesame semiconductor type as the first well region or the second wellregion; forming a first gate and a second gate on the first well regionand the second well region respectively; forming a first doping region,a second doping region and a third doping region in the first wellregion, the second well region and the third well region respectively,the first doping region having the same semiconductor type as the firstwell region, the second doping region having the same semiconductor typeas the second well region, and the third doping region and the thirdwell region having different semiconductor types; forming a resonatecavity in the semiconductor substrate; and forming a first insulatinglayer covering the first gate, the second gate and the resonant cavity;and forming a first source, a first drain, a second source, a seconddrain and a first electrode on the first insulating layer, the firstsource and the first drain being connected with the first doping regionthrough via holes penetrating the first insulating layer, the secondsource and the second drain being connected with the second dopingregion through via holes penetrating the first insulating layer, thefirst electrode being connected with the third doping region through avia hole penetrating the first insulating layer, the first drain beingconnected with the second source, and the second drain being connectedwith the first electrode.

In an embodiment, the step of forming an ultrasonic sensing unit on theresonant cavity comprises: forming a piezoelectric layer on the firstinsulating layer; forming a second insulating layer covering thepiezoelectric layer; and forming a first drive electrode and a seconddrive electrode on the second insulating layer, the first driveelectrode and the second drive electrode being connected with thepiezoelectric layer through via holes penetrating the second insulatinglayer respectively.

In an embodiment, in the step of forming a first drive electrode and asecond drive electrode on the second insulating layer, a first leadwire, a second lead wire and a third lead wire are formed at the sametime, the first lead wire being connected with the first source of thepixel circuit through a via hole penetrating the second insulatinglayer, the second lead wire being connected with the first drain and thesecond source of the pixel circuit through a via hole penetrating thesecond insulating layer, and the third lead wire is connected with thesecond drain of the pixel circuit and the first electrode of thephotosensitive unit through a via hole penetrating the second insulatinglayer.

In an embodiment, the manufacture method further comprises: forming afilter layer, the filter layer including a plurality of filter unitsarranged in an array, each of the filter units being used fortransmitting light of a color.

In an embodiment, the manufacture method further comprises: forming alight collection layer, the light collection layer including a pluralityof lens units arranged in an array, the lens units being used forconverging incident light to the photosensitive unit of the imagesensing unit.

The embodiments of this disclosure provide an image distance sensor anda manufacture method thereof as well as a ranging device, and by formingan image sensing unit and a distance sensing unit on the semiconductorsubstrate in one and the same process, the image sensing function andthe distance sensing function are organically integrated in one sensor,thereby effectively overcoming the defects such as low integration,large volume, high costs and so on in the existing combined solution.

Apparently, any product or process implementing this disclosure may nothave to achieve all of the above advantages at the same time. Otherfeatures and advantages of this disclosure will be detailed in thesubsequent embodiments of the description, and will partly becomeobvious from the embodiments of the description, or be understood bycarrying out this disclosure. Goals and other advantages of theembodiments of this disclosure can be realized and achieved fromstructures specifically pointed out in the description, the claims andthe drawings.

BRIEF DESCRIPTION OF DRAWINGS

The drawings are used to provide further understanding of the technicalsolutions of this disclosure and constitute part of the description.They are used to explain the technical solutions of this disclosureinstead of limiting them. Shapes and sizes of components in the drawingsdo not reflect true ratios, but instead they are only provided toillustrate the content of the disclosure.

FIG. 1 is a schematic structure view of an image distance sensoraccording to an embodiment of this disclosure;

FIG. 2 is a schematic view after the formation of patterns of wellregions according to an embodiment of this disclosure;

FIG. 3 is a schematic view after the formation of patterns of a CMOSgate according to an embodiment of this disclosure;

FIG. 4 is a schematic view after the formation of patterns of dopingregions and a photodiode according to an embodiment of this disclosure;

FIG. 5 is a schematic view after the formation of patterns of a resonantcavity according to an embodiment of this disclosure;

FIG. 6 is a schematic view after the formation of patterns of a firstinsulating layer according to an embodiment of this disclosure;

FIG. 7 is a schematic view after the formation of patterns of a CMOSsource-drain according to an embodiment of this disclosure;

FIG. 8 is a schematic view after the formation of patterns of apiezoelectric layer according to an embodiment of this disclosure;

FIG. 9 is a schematic view after the formation of patterns of a secondinsulating layer according to an embodiment of this disclosure;

FIG. 10 is a schematic view after the formation of patterns of leadwires and drive electrodes according to an embodiment of thisdisclosure;

FIG. 11 is a schematic view after the formation of patterns of a filterlayer according to an embodiment of this disclosure;

FIG. 12 is a schematic view after the formation of patterns of a lightcollection layer according to an embodiment of this disclosure;

FIG. 13 is a schematic structure view of a ranging device according toan embodiment of this disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

The specific implementation of this disclosure will be further explainedin detail with reference to the drawings and the embodiments. Theembodiments below are used for explaining this disclosure rather thanlimiting the scope of this disclosure. It should be noted that theembodiments in this disclosure and the features of the embodiments canbe combined with each other arbitrarily under the circumstances thatthere is no conflict.

FIG. 1 is a schematic structure view of an image distance sensoraccording to an embodiment of this disclosure. As shown in FIG. 1, themain structure of the image distance sensor comprises a plurality ofpixel units 100 arranged in an array. The plurality of pixel units 100are provided with image sensing units 200 for acquiring images anddistance sensing units 300 for acquiring distances. The image sensingunit 200 and the distance sensing unit 300 are formed on a semiconductorsubstrate and manufactured at the same time in one and the samemanufacture process.

In one embodiment, each pixel unit 100 comprises an image sensing unit200 and a distance sensing unit 300 arranged in parallel, the imagesensing unit 200 being formed on one side of the pixel unit 100, and thedistance sensing unit 300 being formed on the other side of the pixelunit 100, which forms an overall layout that the image sensing units 200and the distance sensing units 300 are arranged alternatingly on thesemiconductor substrate.

FIG. 1 only schematically shows a structure of the pixel unit comprisingan image sensing unit and a distance sensing unit arranged in parallel,and according to an embodiment of this disclosure, the pixel unit mayalso have a structure with an up-down arrangement, e.g., the distancesensing unit is on top and the image sensing unit underneath, or viceversa. In another embodiment, it may also have such a structure that apixel unit 100 is provided with an image sensing unit 200 and a furtherpixel unit 100 adjacent thereto is provided with a distance sensing unit300, which also forms an overall layout that the image sensing units 200and the distance sensing units 300 are arranged alternatingly on thesemiconductor substrate. Besides, the image sensing unit and thedistance sensing unit according to the embodiments of this disclosuremay also be arranged such that a plurality of adjacent pixel units 100are provided with an image sensing unit 200 each to form an imagingregion and a pixel unit 100 is provided with a distance sensing unit 300to form a ranging region, the imaging region and the ranging regionbeing arranged alternatingly. Alternatively, a plurality of adjacentpixel units 100 are provided with a distance sensing unit 300 each toform a ranging region and a pixel unit 100 is provided with an imagesensing unit 200 to form an imaging region, the imaging region and theranging region being arranged alternatingly. The adjacent pixel unitscan be either pixel units adjacent in the same row or pixel unitsadjacent in the same column. The alternating arrangement of the imagesensing unit and the distance sensing unit can expand the detectionrange to the maximum extent. In actual implementation, for a structurein which the pixel unit is provided with both an image sensing unit anda distance sensing unit, occupation areas of the two sensing units canbe arranged upon needs of imaging and ranging, e.g., the image sensingunit occupies ¾ of the pixel region, and the distance sensing unitoccupies only ¼ of the pixel region, and so on.

The image sensing unit 200 for acquiring images comprises aphotosensitive unit for sensing visible light and a pixel circuit forprocessing photo-generated charge data, the photosensitive unit and thepixel circuit being connected with each other. The pixel circuit is aComplementary Metal-Oxide Semiconductor (CMOS) circuit, comprising aPositive Channel Metal Oxide Semiconductor (PMOS) transistor and aNegative Channel Metal Oxide Semiconductor (NMOS) transistor. Thephotosensitive unit is used for sensing visible light and performingphotoelectric signal conversion, comprising a PN junction Photo Diode(PD), a heavily doped second semiconductor type region of the photodiodeis located on top of a heavily doped first semiconductor type region.Specifically, when the first semiconductor type is P type and the secondsemiconductor type is N type, the heavily doped N type region (N+region) of the PN junction photodiode is located on top of the heavilydoped P type region (P+ region); when the first semiconductor type is Ntype and the second semiconductor type is P type, the heavily doped Ptype region (P+ region) of the PN junction photodiode is located on topof the heavily doped N type region (N+ region).

The distance sensing unit 300 comprises an ultrasonic sensing unit forgenerating and receiving ultrasonic signals and a resonant cavity forresonating. The ultrasonic sensing unit comprises a piezoelectric layer,and a first drive electrode and a second drive electrode connected withthe piezoelectric layer respectively. The piezoelectric layer is made ofan organic piezoelectric material, including polyvinylidene fluoride(PVDF).

The pixel circuit comprises: a first well region and a second wellregion formed in the semiconductor substrate, the first well regionbeing provided with a first doping region and the second well regionbeing provided with a second doping region, and the first well regionand the second well region having different semiconductor types; a firstgate and a second gate formed on the first well region and the secondwell region; a first insulating layer covering the first gate and thesecond gate; and a first source, a first drain, a second source and asecond drain formed on the first insulating layer. The first source andthe first drain are connected with the first doping region through viaholes penetrating the first insulating layer, the second source and thesecond drain are connected with the second doping region through viaholes penetrating the first insulating layer, and the first drain isconnected with the second source electrode.

The photosensitive unit comprises: a third well region formed in thesemiconductor substrate, the third well region having the samesemiconductor type as either of the first well region and the secondwell region, the third well region being provided with a third dopingregion, the third doping region and the third well region havingdifferent semiconductor types; and a first electrode formed on the thirddoping region, the first electrode being connected with the second drainof the pixel circuit.

The distance sensing unit comprises: a resonant cavity formed in thesemiconductor substrate; a first insulating layer covering the resonantcavity; a piezoelectric layer formed on the first insulating layer; asecond insulating layer covering the piezoelectric layer; and a firstdrive electrode and a second drive electrode formed on the secondinsulating layer. The first drive electrode and the second driveelectrode are connected with the piezoelectric layer through via holespenetrating the second insulating layer respectively. The piezoelectriclayer, the first drive electrode and the second drive electrodeconstitute an ultrasonic sensing unit.

The image distance sensor further comprises a first lead wire, a secondlead wire and a third lead wire formed on the second insulating layer.The first lead wire is connected with the first source of the pixelcircuit through a via hole penetrating the second insulating layer, thesecond lead wire is connected with the first drain and the second sourceof the pixel circuit through a via hole penetrating the secondinsulating layer, and the third lead wire is connected with the seconddrain of the pixel circuit and the first electrode of the photosensitiveunit through a via hole penetrating the second insulating layer.

The image distance sensor further comprises a filter layer, the filterlayer including a plurality of filter units arranged in an array, eachof the filter units being used for transmitting light of a color.

The image distance sensor further comprises a light collection layer,the light collection layer including a plurality of lens units arrangedin an array, the lens units being used for converging incident light tothe photosensitive unit.

In the image distance sensor provided in the embodiments of thisdisclosure, by forming on the semiconductor substrate at the same timein one and the same process an image sensing unit for acquiring imagesand a distance sensing unit for acquiring distances, and arranging theimage sensing unit and the distance sensing unit in a same pixel unit orin different pixels, the image sensing function and the distance sensingfunction are organically integrated in one sensor, thereby effectivelyovercoming the defects such as low integration, large volume, high costsand so on in the existing combined solution, improving the integrationto the maximum extent, decreasing the volume of the product and reducingthe production costs.

FIG. 2˜FIG. 12 are schematic views shown the process of manufacturing animage distance sensor according to the embodiments of this disclosure.

The technical solutions according to the embodiments of this disclosurewill be explained in detail with reference to the manufacture process ofthe image distance sensor as shown in FIG. 2˜FIG. 10. The “patterningprocess” mentioned in each embodiment comprises treatments such asdepositing a film layer, coating with a photoresist, exposing with amask, developing, etching, stripping the photoresist and so on, whichare existing manufacturing processes. The deposition can be knownprocesses such as sputtering, evaporation, chemical vapor deposition,and the coating can be a known coating process, and the etching canadopt a known method, which will not be limited specifically herein.During the manufacture process below, the first semiconductor type is Ptype and the second semiconductor type is N type for example, but themanufacture process is also applicable to a solution in which the firstsemiconductor type is N type and the second semiconductor type is Ptype.

1. Forming patterns of well regions on the semiconductor substrate 10.Forming patterns of well regions comprises: forming a first P wellregion 20, N well region 30 and a second P well region 40 on thesemiconductor substrate 10 by an ion implantation process as shown inFIG. 2. The first P well region and the second P well region can beobtained by implanting P-type ions in a predetermined region of thesemiconductor substrate 10, and the N well region can be obtained byimplanting N-type ions in a predetermined region of the semiconductorsubstrate 10.

The semiconductor substrate can be any of a silicon substrate, agermanium substrate and a silicon germanium substrate, or any of aSilicon On Insulator (SOI) substrate, a Germanium On Insulator (GOI)substrate and a Silicon Germanium On Insulator (SGOI) substrate, and itis not limited thereto.

The semiconductor substrate may also have a structure of a semiconductorlayer formed on a transparent substrate, or a buffer layer and asemiconductor layer formed on a transparent substrate, and thetransparent substrate can be a glass substrate, a quartz substrate, anorganic resin substrate or the like, and the buffer layer can be asilicon nitride layer, a silicon oxide layer, a silicon oxynitride layeror a composite layer thereof.

2. Forming patterns of a CMOS gate. Forming patterns of a CMOS gatecomprises: based on the formation of the above patterns, afterdepositing a polysilicon layer, performing doping treatment first, andthen forming patterns of a first gate 21 and a second gate 31 by apatterning process, as shown in FIG. 3. The first gate 21 is located inthe first P well region 20 as a polysilicon gate of a PMOS transistor,and the second gate 31 is located in the N well region 30 as apolysilicon gate of an NMOS transistor. Forming patterns of a first gateand a second gate by a patterning process can comprise: coating thepolysilicon layer with a layer of photoresist, exposing and developingthe photoresist, forming an unexposed region and retaining thephotoresist in a position where the first gate and the second gate arelocated, forming a fully exposed region and removing the photoresist inother regions, etching the polysilicon layer in the fully exposed regionby an etching process, stripping the remnant photoresist, and formingpatterns of a first gate and a second gate.

Deposition of the polysilicon layer can also be implemented by othermethods. For example, an amorphous silicon layer can be deposited first,and then treatments such as dehydrogenation and excimer laser annealingare performed on the amorphous silicon layer to convert amorphoussilicon into polysilicon, thereby forming a polysilicon layer. Besides,the first gate and the second gate can also be made of metal materials.

3. Forming patterns of doping regions and a photodiode. Forming patternsof doping regions and a photodiode comprises: based on the formation ofthe above patterns, applying a layer of photoresist, exposing anddeveloping the photoresist, performing doping treatment by ionimplantation, forming a first doping region 22 in the first P wellregion 20, forming a second doping region 32 in the N well region 30,and forming a third doping region 41 in the second P well region 40, asshown in FIG. 4.

The first doping region 22 is P-type ion doped and located on both sidesof the first gate 21 as the source and the drain of the PMOS transistorsuch that a region of the first P well region 20 beneath the first gate21 serves as the channel of the PMOS transistor. The second dopingregion 32 is N-type ion doped and located on both sides of the secondgate 31 as the source and the drain of the NMOS transistor such that aregion of the N well region 30 beneath the second gate 31 serves as thechannel of the NMOS transistor. The third doping region 41 is N-type iondoped and located within part of the second P well region 40 such thatthe second P well region 40 and the N-type semiconductor formed thereonconstitute a PN junction of a photodiode and form a photodiode 42, andthe other part of the second P well region 40 is a light receptionsurface that receives visible light to generate carriers passing througha spatial charge region of the PN junction and thus generate aphotoelectric current, thereby achieving visible light detection.

The first doping region, the second doping region and the third dopingregion can be obtained by implanting N-type ions or P-type ions in apredetermined region respectively, and depths of the ions implanted canbe either the same or different, and concentrations of the ions dopedcan be either the same or different, which will not be specificallylimited herein. The process of forming well regions and doping regionsby ion implantation is well known for those skilled in the art, whichwill not be elaborated herein for simplicity.

4. Forming patterns of a resonant cavity. Forming patterns of a resonantcavity comprises: based on the formation of the above patterns, applyinga layer of photoresist, exposing and developing the photoresist, forminga fully exposed region and removing the photoresist in a position wherethe patterns of the resonant cavity are located, forming an unexposedregion and retaining the photoresist in other regions, etching part ofthe thickness of the semiconductor substrate in the fully exposed regionby an etching process, stripping the remnant photoresist, and formingpatterns of a resonant cavity 51 in the semiconductor substrate 10, asshown in FIG. 5. The etching can be performed by an Inductively CouplePlasma Etch (ICP) approach and thus etching of the resonant cavity canbe achieved by taking advantage of the characteristics of the ICPapproach such as anisotropy, high etch rate, high etch selectivity withrespect to different materials, controllability of the process and soon.

5. Forming patterns of a first insulating layer. Forming patterns of afirst insulating layer comprises: based on the formation of the abovepatterns, depositing a first insulating layer 11 and forming patterns ofa plurality of via holes in the first insulating layer 11 by apatterning process, as shown in FIG. 6. The plurality of via holes arelocated in the first doping region 22 of the first P well region 20, thesecond doping region 32 of the N well region 30 and the third dopingregion 41 of the second P well region 40 respectively. The firstinsulating layer can be a silicon nitride layer, a silicon oxide layer,a silicon oxynitride layer or a composite layer thereof.

6. Forming patterns of a CMOS source-drain. Forming patterns of a CMOSsource-drain comprises: based on the formation of the above patterns,depositing a first metal layer, and forming on the first insulatinglayer 11 patterns of a first source 23, a first drain 24, a secondsource 33, a second drain 34 as well as a first electrode 43 of thephotodiode 42 respectively by performing a patterning process on thefirst metal layer. The first source 23 and the first drain 24respectively serve as the source and the drain of the PMOS transistor,and the second source 33 and the second drain 34 respectively serve asthe source and the drain of the NMOS transistor. The source 23 of thePMOS transistor and the drain 24 of the PMOS transistor are connectedwith the first doping region 22 of the first P well region 20 throughvia holes penetrating the first insulating layer 11 respectively, andthe source 33 of the NMOS transistor and the drain 34 of the NMOStransistor are connected with the second doping region 32 of the N wellregion 30 through via holes penetrating the first insulating layer 11respectively, the first electrode 43 of the photodiode 42 is connectedwith the third doping region 41 of the second P well region 40 through avia hole penetrating the first insulating layer 11, and the drain 24 ofthe PMOS transistor is connected with the source 33 of the NMOStransistor, and the drain 34 of the NMOS transistor is connected withthe first electrode 43 of the photodiode 42, as shown in FIG. 7.

After the above procedures, a CMOS circuit and a photodiode connectedwith each other are formed, wherein the CMOS circuit comprises a PMOStransistor and an NMOS transistor connected with each other, the PMOStransistor serving as a PMOS readout circuit and the NMOS transistorserving as an NMOS readout circuit. The PMOS transistor comprises afirst gate 21, a source 23, a drain 24 and a channel, and the NMOStransistor comprises a second gate 31, a source 33, a drain 34 and achannel. In the CMOS circuit, either of the NMOS transistor and the PMOStransistor is turned on, or both transistors are turned off, so thepower consumption is very low.

In the embodiments of this disclosure, the photosensitive unit is aphotodiode having a PN structure which has advantages such as goodlinearity, low noise, low costs, long service life and low operatingvoltage. The operation principle of a photodiode having a PN structureis that an ordinary diode is in an OFF state under the effect of areverse voltage so only passage of a weak reverse current is allowed,while a photodiode is designed and manufactured such that an area of thePN junction is as large as possible in order to receive incident light.The photodiode can operate under the effect of the reverse voltage, andwhen there is no light, the reverse current is very weak, which iscalled dark current; when there is light, the reverse current rapidlyincreases to several dozen microamp, which is called photocurrent. Thegreater the intensity of light is, the greater the reverse current is.Changes in light lead to changes in the current of the photodiode, andthe photodiode can convert light signals into electrical signals andhence becomes a photosensor. In actual implementation, the PN junctionof the photodiode can also be mixed with a layer of semiconductor havinga low concentration, thereby forming a photodiode with a PIN structure.For a photodiode with a PN structure, the P-type semiconductor and theN-type semiconductor can either have a stack structure as in thisembodiment, or have a same layer structure. Besides, in order to reduceinterference, an opaque pattern can also be formed on the semiconductorsubstrate such that an orthogonal projection of the photodiode on thesemiconductor substrate is located within an orthogonal projection ofthe opaque pattern on the semiconductor substrate.

In the embodiments of this disclosure, the N-type ions doped in theN-type semiconductor of the photodiode are the same as the N-type ionsdoped in the N-type semiconductor of the NMOS transistor, and are dopedin one and the same doping process, and the first electrode of thephotodiode, the source and the drain of the PMOS transistor and thesource and the drain of the NMOS transistor are formed in one and thesame patterning process, so the manufacture process is simplified. Forother types of transistors, the manufacture process is similar to theabove manufacture process, and for those skilled in the art, severalimprovement and expansion can also be made without deviating from theprinciple of this disclosure, and such improvement and expansion shouldalso be regarded as solutions of this disclosure.

7. Forming patterns of a piezoelectric layer. Forming patterns of apiezoelectric layer comprises: based on the formation of the abovepatterns, depositing a piezoelectric material layer and forming patternsof a piezoelectric layer 52 in a position corresponding to the patternsof the resonant cavity 51 on the first insulating layer 11 by performinga patterning process on the piezoelectric material layer, as shown inFIG. 8. The piezoelectric layer can be made of an organic piezoelectricmaterial such as polyvinylidene fluoride (PVDF), or a piezoelectricceramic material such as aluminum magnesium niobate, or a lead zirconatetitanate piezoelectric ceramic composite crystal (PZT) material,aluminum nitride or the like.

8. Forming patterns of a second insulating layer. Forming patterns of asecond insulating layer comprises: based on the formation of the abovepatterns, depositing a second insulating layer 12 and forming patternsof a plurality of via holes in the second insulating layer 12 by apatterning process, as shown in FIG. 9. The plurality of via holes arelocated on the source 23 of the PMOS transistor, the source 33 of theNMOS transistor, the first electrode of the photodiode 42 and both sidesof the piezoelectric layer 52. The second insulating layer can be asilicon nitride layer, a silicon oxide layer, an aluminum oxide layer, asilicon oxynitride layer or a composite layer thereof.

9. Forming patterns of lead wires and drive electrodes. Forming patternsof lead wires and drive electrodes comprises: based on the formation ofthe above patterns, depositing a second metal layer, and forming on thesecond insulating layer 12 patterns of a first lead wire 25, a secondlead wire 35, a third lead wire 44, a first drive electrode 53 and asecond drive electrode 54 respectively by performing a patterningprocess on the second metal layer, as shown in FIG. 10. The first leadwire 25 is connected with the source 23 of the PMOS transistor through avia hole penetrating the second insulating layer 12, the second leadwire 35 is connected with the drain 24 of the PMOS transistor and thesource 33 of the NMOS through a via hole penetrating the secondinsulating layer 12, and the third lead wire 44 is connected with thedrain 34 of the NMOS transistor and the first electrode 43 of thephotodiode 42 through a via hole penetrating the second insulating layer12, and the first drive electrode 53 and the second drive electrode 54are connected with both ends of the piezoelectric layer 52 through viaholes penetrating the second insulating layer respectively.

After the above procedures, a distance sensing unit for acquiringdistance parameters is formed. The distance sensing unit comprises aresonant cavity 51 formed in the semiconductor substrate and anultrasonic sensing unit. The ultrasonic sensing unit comprises apiezoelectric layer 52, a first drive electrode 53 and a second driveelectrode 54, the first drive electrode 53 and the second driveelectrode 54 being connected with the piezoelectric layer 52respectively, and the first insulating layer 11 between the resonantcavity 51 and the piezoelectric layer 52 serving as a barrier layer.

The distance sensing unit in the embodiments of this disclosure is alsocalled an ultrasonic transducer which is used for generating ultrasonicsignals and receiving ultrasonic signals reflected from an obstacle andconverting them into electrical signals. The volume structure of theresonant cavity depends on its design, and once it is designed, itsresonant frequency is fixed. When the frequency of the ultrasonic wavesgenerated by the ultrasonic sensing unit is the same as that of theresonant cavity, resonance occurs in the resonant cavity, whichincreases the amplitude of the ultrasonic waves such that the amplitudeis maximized after the ultrasonic waves pass through the resonantcavity. In an ultrasonic generating stage, a signal processing circuitprovides a pulse electrical signal which is transmitted to the firstdrive electrode and the second drive electrode via a drive line suchthat an inverse piezoelectric effect occurs in the piezoelectric layerof the ultrasonic sensing unit, and high-frequency mechanicaldeformation generates ultrasonic waves which propagate to the resonantcavity. Since the frequency of the ultrasonic waves is the same as theinherent frequency of the resonant cavity, the ultrasonic waves passingthrough the resonant cavity resonate, which increases the amplitude ofthe ultrasonic waves before they are transmitted outwards. In anultrasonic receiving stage, since the ultrasonic waves are reflectedwhen they meet an obstacle and the reflected ultrasonic waves aresignals having a certain sound pressure, the piezoelectric layer isdeformed, and the piezoelectric layer is excited by the in-planeoscillation to generate voltage signals which are transmitted to anexternal signal processing circuit by a sensing signal line. Bycalculating a time difference between the transmitting time of theultrasonic waves and the receiving time thereof, the signal processingcircuit can obtain distance parameters of the obstacle. The principle ofreceiving and converting the reflected ultrasonic signals by theultrasonic transducer is well known for those skilled in the art, whichwill not be elaborated herein for simplicity.

10. Forming patterns of a filter layer. Forming patterns of a filterlayer comprises: based on the formation of the above patterns,depositing a third insulating layer 13 first, then sequentially applyingred, green and blue photoresists, and forming a filter layer 14comprising a plurality of filter units by a patterning process, as shownin FIG. 11. In the embodiments of this disclosure, the plurality offilter units are arranged in an array, and each filter unit is mainlyused for transmitting light of a color and filtering light of othercolors such that each pixel unit only responses to light of a color,which improves the photosensitive performance of the photodiode. Forexample, for red light, green light and blue light, each filter unitonly allows one of them to pass through. The third insulating layer canbe a silicon nitride layer, a silicon oxide layer, a silicon oxynitridelayer or a composite layer thereof.

11. Forming patterns of a light collection layer. Forming patterns of alight collection layer comprises: based on the formation of the abovepatterns, applying a transparent thin film, and forming a lightcollection layer 15 comprising a plurality of lens units by a patterningprocess, as shown in FIG. 12. The plurality of lens units are arrangedin an array, and each lens unit comprises one or more microlensstructures for converging the incident light into the photosensitiveunit, the position and the size of the microlens structurescorresponding to the position and the size of the photodiode 42. In theembodiments of this disclosure, the lens unit is mainly used forconverging the incident light, collecting more incident light onto thesurface of the photodiode, increasing the intensity of light impingingon the photodiode, improving the photosensitive performance of thephotodiode and increasing the sensitivity of the pixel unit.

Although the technical solutions of the embodiments of this disclosureare illustrated above by forming patterns of the well regions on thesemiconductor substrate first, the structure and the manufacture methodof the image distance sensor of the embodiments of this disclosure arenot limited thereto. In fact, all structures and manufacture methods ofthe existing CMOS circuits, and all structures and manufacture methodsof the existing ultrasonic transducers are applicable to the embodimentsof this disclosure, which will not be elaborated herein for simplicity.

As can be seen from the above explanations, in the image distance sensorprovided in the embodiments of this disclosure, by forming an imagesensing unit for acquiring images and a distance sensing unit foracquiring distances on the semiconductor substrate at the same time inone and the same process, the image sensing function and the distancesensing function are organically integrated in one sensor, therebyeffectively overcoming the defects such as low integration, largevolume, high costs and so on in the existing combined solution. Sincethe image sensing unit and the distance sensing unit can be arranged ina same pixel unit or in different pixels, the integration is improved tothe maximum extent, which truly realizes an integrated structure andreduces the product volume. Since the doping treatment of the photodiodeand the doping treatment of the PMOS transistor and the NMOS transistorare carried out in one and the same doping process, the first electrodeof the photodiode, the source and the drain of the PMOS transistor andthe source and the drain of the NMOS transistor are formed in one andthe same patterning process, and the first drive electrode and thesecond drive electrode of the ultrasonic sensing unit and the lead wiresof the pixel circuit are formed in one and the same patterning process,the production costs are effectively reduced. Besides, the arrangementof a filter layer and a light collection layer improves thephotosensitive performance of the photodiode and improves thesensitivity of the pixel unit.

Based on the technical concept of the embodiments of this disclosure, amanufacture method of an image distance sensor is further provided inthe embodiments of this disclosure. The manufacture method of an imagedistance sensor comprises: forming an image sensing unit and a distancesensing unit on a semiconductor substrate in one and the samemanufacture process.

Forming an image sensing unit and a distance sensing unit on asemiconductor substrate in one and the same manufacture processcomprises:

S1, forming on the semiconductor substrate a pixel circuit and aphotosensitive unit of the image sensing unit, and a resonant cavity ofthe distance sensing unit;

S2, forming an ultrasonic sensing unit on the resonant cavity.

Step S1 comprises:

S11, forming in the semiconductor substrate a first well region, asecond well region and a third well region, the first well region andthe second well region having different semiconductor types, and thethird well region having the same semiconductor type as the first wellregion or the second well region;

S12, forming a first gate and a second gate on the first well region andthe second well region respectively;

S13, forming a first doping region, a second doping region and a thirddoping region in the first well region, the second well region and thethird well region respectively, the first doping region having the samesemiconductor type as the first well region, the second doping regionhaving the same semiconductor type as the second well region, and thethird doping region and the third well region having differentsemiconductor types;

S14, forming a resonate cavity in the semiconductor substrate;

S15, forming a first insulating layer covering the first gate, thesecond gate and the resonant cavity;

S16, forming a first source, a first drain, a second source, a seconddrain and a first electrode on the first insulating layer, the firstsource and the first drain being connected with the first doping regionthrough via holes penetrating the first insulating layer, the secondsource and the second drain being connected with the second dopingregion through via holes penetrating the first insulating layer, thefirst electrode being connected with the third doping region through avia hole penetrating the first insulating layer, the first drain beingconnected with the second source, and the second drain being connectedwith the first electrode.

Step S2 comprises:

S21, forming a piezoelectric layer on the first insulating layer;

S22, forming a second insulating layer covering the piezoelectric layer;

S23, forming a first drive electrode and a second drive electrode on thesecond insulating layer, the first drive electrode and the second driveelectrode being connected with the piezoelectric layer through via holespenetrating the second insulating layer.

When the first drive electrode and the second drive electrode are formedon the second insulating layer, a first lead wire, a second lead wireand a third lead wire are formed at the same time, the first lead wirebeing connected with the first source of the pixel circuit through a viahole penetrating the second insulating layer, the second lead wire beingconnected with the first drain and the second source of the pixelcircuit through a via hole penetrating the second insulating layer, andthe third lead wire is connected with the second drain of the pixelcircuit and the first electrode of the photosensitive unit through a viahole penetrating the second insulating layer.

The manufacture method further comprises: forming a filter layer, thefilter layer including a plurality of filter units arranged in an array,each of the filter units being used for transmitting light of a color.

The manufacture method further comprises: forming a light collectionlayer, the light collection layer including a plurality of lens unitsarranged in an array, the lens units being used for converging incidentlight to the photosensitive unit of the image sensing unit.

The specific content of the manufacture method of an image distancesensor according to the embodiments of this disclosure has beenintroduced in detail in the manufacture process of the image distancesensor, which will not be repeated herein for simplicity.

The embodiments of this disclosure further provides a ranging device,the ranging device comprising any image distance sensor according to theabove embodiments. The image distance sensor comprises a plurality ofpixel units arranged in an array, the plurality of pixel units beingprovided with an image sensing unit for acquiring images and a distancesensing unit for acquiring distances. When each pixel unit comprises animage sensing unit and a distance sensing unit, the image sensing unitis formed on one side of the pixel unit and the distance sensing unit isformed on the other side of the pixel unit, which forms an overalllayout that the image sensing units and the distance sensing units arearranged alternatingly. When a pixel unit is provided with an imagesensing unit and a further pixel unit adjacent thereto is provided witha distance sensing unit, an overall layout that the image sensing unitsand the distance sensing units are arranged alternatingly is alsoformed.

The overall layout that the image sensing units and the distance sensingunits are arranged alternatingly can achieve separate control of theimage sensing units and the distance sensing units by arranging aplurality of independent drive lines between the pixel units incombination with respective external processing circuits, therebyachieving high integration of the reverse radar ranging function and thereverse image display function. FIG. 13 is a schematic structure view ofa ranging device according to an embodiment of this disclosure. As shownin FIG. 13, the external processing circuit comprises a perpendicularaccess circuit, a horizontal access circuit, a receiving circuit, areadout circuit, a probe sensing circuit, a digital processing circuitand so on. Common designs of the art can be adopted for the layout ofthe external processing circuit and the circuit structure of thespecific circuit, which will not be elaborated for simplicity.

In the description of this disclosure, it should be understood thatdirectional or positional relations indicated by terms such as “center”,“up”, “down”, “front”, “rear”, “vertical”, “horizontal”, “top”,“bottom”, “inner” and “outer” are directional or positional relationsshown on the basis of the drawings. They are used only for describingthis disclosure and simplifying the description, instead of indicatingor implying that the indicated devices or elements must be orientatedspecifically, or constructed and operated in a specific orientation, sothey cannot be construed as limiting this disclosure.

In the description of this disclosure, it should be noted that terms of“install”, “link” and “connect” should be understood in a broad senseunless otherwise prescribed and defined explicitly. For example,“connect” can refer to fixed connection, or detachable connection, orintegrated connection; it can also refer to mechanical connection orelectrical connection; or direct connection, or indirect connection viaintermediate media, or even connection inside two elements. For a personhaving ordinary skills in the art, the specific meanings of the aboveterms in this disclosure can be understood upon specific situations.

Although the implementations of this disclosure are disclosed above, thecontents thereof only relate to implementations adopted forunderstanding this disclosure instead of limiting this disclosure. Anyskilled person in the art of this disclosure can make any modificationsand variations in terms of forms and details of the implementationswithout deviating from the spirits and scopes disclosed in thisdisclosure. The protection scope of this disclosure is subjected to thescope defined in the appended claims.

The invention claimed is:
 1. An image distance sensor, comprising: asemiconductor substrate; an image sensing unit; and a distance sensingunit formed on the semiconductor substrate, wherein the image sensingunit and the distance sensing unit are formed in a same manufactureprocess, wherein the image sensing unit comprises a pixel circuit and aphotosensitive unit formed on the semiconductor substrate, and whereinthe pixel circuit comprises: a first well region and a second wellregion formed in the semiconductor substrate, the first well regioncomprising a first doping region and the second well region comprising asecond doping region, wherein the first well region and the second wellregion having different semiconductor types; a first gate and a secondgate on the first well region and the second well region; a firstinsulating layer on the first gate and the second gate; and a firstsource, a first drain, a second source and a second drain on the firstinsulating layer, wherein the first source and the first drain areconnected to the first doping region through via holes penetrating thefirst insulating layer, wherein the second source and the second drainare connected to the second doping region through the via holespenetrating the first insulating layer, wherein the first drain isconnected to a second source electrode, and wherein the photosensitiveunit comprises: a third well region in the semiconductor substrate,wherein the third well region comprises a third doping region, andwherein the third doping region and the third well region have differentsemiconductor types; and a first electrode on the third doping region,the first electrode being connected to the second drain of the pixelcircuit.
 2. The image distance sensor according to claim 1, furthercomprising: a filter layer, wherein the filter layer comprises aplurality of filter units arranged in an array, and wherein each of thefilter units is configured to transmit light of a respective color. 3.The image distance sensor according to claim 1, further comprising: alight collection layer, wherein the light collection layer comprises aplurality of lens units arranged in an array, and wherein the pluralityof lens units are configured to converge incident light to aphotosensitive unit of the image sensing unit.
 4. A ranging devicecomprising the image distance sensor according to claim
 1. 5. Theranging device according to claim 4, wherein the image sensing unitfurther comprises: a filter layer, wherein the filter layer comprises aplurality of filter units arranged in an array, and wherein each of thefilter units is configured to transmit light of a respective color. 6.An image distance sensor, comprising: a semiconductor substrate; animage sensing unit; and a distance sensing unit formed on thesemiconductor substrate, wherein the image sensing unit and the distancesensing unit are formed in a same manufacture process, wherein the imagesensing unit comprises a pixel circuit and a photosensitive unit formedon the semiconductor substrate, and wherein the pixel circuit comprises:a first well region and a second well region formed in the semiconductorsubstrate, the first well region comprising a first doping region andthe second well region comprising a second doping region, wherein thefirst well region and the second well region having differentsemiconductor types; a first gate and a second gate on the first wellregion and the second well region; a first insulating layer on the firstgate and the second gate; and a first source, a first drain, a secondsource and a second drain on the first insulating layer, wherein thefirst source and the first drain are connected to the first dopingregion through via holes penetrating the first insulating layer, whereinthe second source and the second drain are connected to the seconddoping region through the via holes penetrating the first insulatinglayer, wherein the first drain is connected to a second sourceelectrode, wherein the distance sensing unit comprises: a resonatecavity in the semiconductor substrate; a first insulating layer on theresonate cavity; a piezoelectric layer on the first insulating layer; asecond insulating layer on the piezoelectric layer; and a first driveelectrode and a second drive electrode on the second insulating layer,wherein the first drive electrode and the second drive electrode areconnected to the piezoelectric layer through via holes penetrating thesecond insulating layer respectively.
 7. The image distance sensoraccording to claim 6, further comprising: a first lead wire, a secondlead wire and a third lead wire formed on the second insulating layer,wherein the first lead wire is connected to the first source of thepixel circuit through a first via hole of the via holes penetrating thesecond insulating layer, wherein the second lead wire is connected tothe first drain and the second source of the pixel circuit through asecond via hole of the via holes penetrating the second insulatinglayer, and wherein the third lead wire is connected to the second drainof the pixel circuit and a first electrode of the photosensitive unitthrough a third via hole of the via holes penetrating the secondinsulating layer.
 8. A ranging device comprising the image distancesensor according to claim
 6. 9. The ranging device according to claim 8,wherein the image sensing unit further comprises: a first lead wire, asecond lead wire and a third lead wire on the second insulating layer,wherein the first lead wire is connected to the first source of thepixel circuit through a first via hole of the via holes penetrating thesecond insulating layer, wherein the second lead wire is connected tothe first drain and the second source of the pixel circuit through asecond via hole of the via holes penetrating the second insulatinglayer, and wherein the third lead wire is connected to the second drainof the pixel circuit and a first electrode of the photosensitive unitthrough a third via hole of the via holes penetrating the secondinsulating layer.
 10. The ranging device according to claim 8, whereinthe image sensing unit further comprises: a filter layer, wherein thefilter layer comprises a plurality of filter units arranged in an array,and wherein each of the filter units is configured to transmit light ofa respective color.
 11. The image distance sensor according to claim 6,further comprising: a filter layer, wherein the filter layer comprises aplurality of filter units arranged in an array, and wherein each of thefilter units is configured to transmit light of a respective color. 12.The image distance sensor according to claim 6, further comprising: alight collection layer, wherein the light collection layer comprises aplurality of lens units arranged in an array, and wherein the pluralityof lens units are configured to converge incident light to aphotosensitive unit of the image sensing unit.